5. Conservation of energy
Conservation of mechanical energy
let v be a vector associated to vertical velocity of an object
- the object can go up
- If v - gt = 0 the object stops.
- the object can go down
We can define two quantities
Kinetic energy = 1/2 mv^2
Potential energy = accumulates as the object moves upwards
When the object goes up, the kinetic energy decreases because its decelerating but the potential energy is increasing
When the object goes down, its accelerating. Kinetic energy goes up and potential energy goes down.
Conservative forces
- The work done by a conservative force on an object that moves from point x to point y is independent on the path???
- The work done on a close circuit is zero???
These are gravity and elastic force
A conservative force is always the result of variation in potential energy.
A force is always gonna have the direction of minimizing potential energy.
This is called potential difference. Forces close the potential differences.
F(x) =
and
Conservation
In a system of conservative forces nothing is lost:
if newtonians mechanics are at work, mechanical energy is conserved, in order for mechanical energy to be conserved we need to satisfy the second law of newton.
Non-conservative force
The work done on a system does not transform into potential or potential energy, it is transformed into internal energy (Dissipation).
For example friction is not a conservative force, the more io put work in a system with friction the more energy it dissipates, it is not preserved.
Spring potential
Gravitational potential
What the actual fuck is this?
